Sodomy is the word we must use to remind people what they are embracing and of its inherit fallacys.
Do not describe without that word to add historic condemnation this evil.
As for the fate of our civilization, I think you miss the positive effect of the culturally more isolated and religious immigrant population. A population that will no doubt continue to support values and if we can ever get their heads out of their ass may even begin voting for rather than against their own values.
As for the black population, no population is homogenus if we can break the race barrier with Latinos we may also find ways to break it with black.
If all else fails and we end up abandoning the republican party label and instead overrunning the Democratic party. We may very well bypass the racist firewall by acting as chameleon only distinguishable by our values & polices, which we know they share & agree with.
The future is not as dark as you suppose. Rather by changing the way we play this otherwise rigged game it can be very bright indeed.
Perhaps there is a way for people who believe in something to translate their beliefs into political action that will be transformative. I personally doubt it absent some real true calamities descending on the complacent, shallow, pleasure loving sensualists that far to much of the population of our country have become.